Problem: Combine like terms to create an equivalent expression. ${-\dfrac{2}{3}a+\dfrac56a-\dfrac16}$
Answer: Combine the $\text{{coefficients}}$ of the $a$ terms. $\phantom{=}{{-\dfrac{2}{3}}a+{\dfrac56}a-\dfrac16}$ $=\left({-\dfrac{2}{3}}+{\dfrac56}\right)\cdot a-\dfrac16$ ${=}\left({-\dfrac{4}{6}}+{\dfrac56}\right)\cdot a-\dfrac16$ $=\left({\dfrac{1}{6}}\right)\cdot a-\dfrac16$ $=\dfrac{1}{6}a-\dfrac16$ The simplified expression is $\dfrac{1}{6}a-\dfrac16$